1. Field of the Invention
The present invention generally relates to a technology for transmitting data using an internet protocol (IP), and more specifically relates to error correction coding of the data.
2. Description of the Related Art
Images and sounds can be transmitted using an internet protocol (IP). When the images and sounds are transmitted through the Internet, because real-time reproduction is often required, the User Datagram Protocol (UDP), which does not involve retransmitting control, is often employed as the standard protocol.
For example, to certain areas like deep valleys, where the digital spectrum does not reach properly, television (TV) programs can be streamed in the form of the UDP packets via optical networks. In other words, the broadcasting and the telecommunication are so closely related that they are almost integrated.
One of the most important techniques employed in both the broadcasting and the telecommunication is the error correction technique. With the error correction technique, a transmitter performs an error correction coding on a data, and a receiver decodes the error-correction coded data, whereby an error occurred during data transmission is corrected. During transmission of data such as images and sounds, modulation methods and error-correction coding method can be changed as disclosed in Japanese Patent Laid-Open Publication No. 2000-115085.
When a TV program is streamed via the Internet, a limited bandwidth is shared with the existing internet communication line and the like, and sufficient bandwidth can hardly be allocated to the broadcasting. It becomes therefore important for the broadcasting to take most advantage of the limited bandwidth to correctly transmit highly prioritized data because the broadcasting needs to be provided in real time.
With the general error correction technique, however, while errors occurred in a small range of the data can be corrected, errors deriving from loss of a whole packet or the like cannot be corrected. The error-correction coding method generally used for broadcasting is suitable for correcting bit errors, which cannot correct errors sufficiently when packets of data are transmitted through the Internet.